Dispenser for viscous products

ABSTRACT

An electric motor driven piston member effects displacement of viscous semiliquid product from its shipping vessel into either of a pair of pump cylinders whose pistons are alternately power driven to expel the product to a delivery line. The pistons of hydraulic actuator cylinders drive the pump pistons under the control of a reversing valve which is reversed each time one of the actuator pistons completes its drive stroke. The electric motor that drives the product-displacing piston member is deenergized whenever the latter effects bodily displacement of the product vessel beyond a predetermined range of motion.

i United States Patent 72 Inventor 2,428,035 9/1947 Palm 222/61 3224 S. 92nd St., Milwaukee, Wis. 53227 2,631,761 3/ 1953 Gates 222/390 [2|] Appl. No. 775,438 3,056,179 10/1962 Lordng.. 222/63 [22] Filed Nov. 13, 1968 3,104,031 9/1963 Wagner 222/390X [45] Patented 1971 Primary Examiner-Robert B. Reeves Assistant Examiner-Norman L. Stack, Jr. Attorney-Ira Milton Jones [54] DISPENSER FOR VISCOUS PRODUCTS 12 Claims, 1 Drawing Fig.

ABSTRACT: An electric motor driven piston member effects [52] U.S. Cl 222/61, di lacement of viscous semiliquid product from its shipping 222/390 vessel into either of a air of um c linders whose istons are 51 1 Cl p p p y p nt. 867d 5/18 l r l ower driven to expel the product to a delivery [50] Field of Search ZZZ/61,63, m The pistons f hydraulic actuator cylinders drive the 390, 379, 258, 262, 405; pump pistons under the control of a reversing valve which is 103/(lnqmred); 141/192, 95 reversed each time one of the actuator pistons completes its [561 cm 3213;";25233:5155;122:2522; 11:22:23 21532:-

UNITED STATES PATENTS fects bodily displacement of the product vessel beyond a 1,567,825 12/ l 925 Williams 222/262X predetermined range of motion.

51M 52 e 43 t 49 REVE RSIMG V 50 M P RES. 4s

-r ZZ- KG Harold Karl Steiner without, rupturing or evenobjectionablebulging.

DISPENSER m v scous PRODUC S.

This inventionrelatestodispensers, and hasm oreparticular reference to power cperated dispensing apparatus, capable of dispensing aviscous semiliquid productdirec tlytthe vesselin which the product is shipped. 1

One. such dispenser isydisclosed ,in my U.S.- PatyNo. 3,28l,020 dated Oct 25, 196p. Thedispenser of, that, patent was particularly design'cd to dispense such semiliquid and viscous productsmsepoxy mortar and causing-compounds .such as are used in the building trades,;directly from the five gallon containers' injwhich ithose products" areordinarily shippedrThe provision of, a significantly improved dispenser ofthat typeconstitutes primaryobject of this invention, I

In the dispenserof my aforesaid.patenc semiliquid product 1 The basern'ember s is y ieldingly supported. from the be; plate 10' of abase structure'l l by means of ahumber of relatively strongcoild compression springs 12. The, spr ngs adapted to yield'a'nd allow the base] member to bedepressed t toward the bedplate when 'product displacing force "of. a

predetermined magnitude is applied tothe body of product confined between the underside of the piston member .8 and V the bottom of the fves sel7 in which the product iscontained. I

is displaced from the ves l containing thesameand throughia port in a piston rnemhen bearing upon the. surface oftheproduct, in consequence *of relative-movement between the pistonjmeinber and base-member upon which the vessel is supported. Because the product was also "forced through'fa delivery line to the point of use in consequence of such rela-u' tive movement betweenthe base- :and piston members; the

force e tpended uponthe product inthe vesselwas'aptto beof such magnitude as o cause bulgingand even rupturing of the cylindricalsidewall of the vessel; ,lnteitherevent, it would be impossible to thereaftercontinue dispensing oftheproducti In contrast, itisa purpose 'of thiszinven'tionto provide animproved dispensing apparatus featuring "indepeiidentfirst and second force ,;applying,nie ans for respectively effecting. dispIacement of viscous product from thevessel containing the same, and forthe'reafter effecting forceful flow of the disreduced force-which the'sidewallsof the vessel can easily bear In a more specific sense, it is a further object character described featuring drive means for concurrentlyeffecting productdisplacing motion of a piston member into a vessel containing theproduct to be dispensed, along with loading of spring 'means'having, a; restoring for e great enough to effect. product-displacing motion of :the;vesse l.relative tothe piston member "at times when the drive means is rendered in-' operative, I

Still another'object of the invention resides'in the'provision I of means for rendering inoperative-the drive-means mentioned .in the preceding-object, ini consequenceof loading spring exemplify to-a predetermined degree, r

. With these observations and objects. in mind, the manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying draw ing. This disclosure is intended merely to exemplify the invenwithin the scope'of the appended claimswithout departing from the invention.

- The drawing illustrates one complete example of the physical embodiment of the invention constructed according to the .best mode so far devised for the practical application of the principles thereof, and in which: i

of shaman tion to provide an improved dispensingapparatus of the of .said

] placed product through a delivery line tothe point of use. As a i result, it is possible for the apparatus of this invention to effect I displacement of the product, from a vessel under greatly r "a mannertohelater'descrihed The piston membersf rigidlycar r i The piston member is rigidly 'carried'by a'platen or pressure head '14. In turn, the pressure headissupported'from the bed plate 10 for up and down motion relative thereto, by three or moreangularly e'quispaced upright drive shafts 1 5.1The lower endp'ortio'ns of the drive shafts are'freely rotatably but axially immovably mounted in the bed plate") and therefrom at locations alongside the periphery of the b ase member $.Screw .threade'd connections, between the upper" end portions of the and the pressure head 14 provide forthe transmission of up or down translating motion to theflpressure head, depend-' ingupon whether the shafts are rotated clockwise or counterclockwise'in unison.

;I Such rotation is transmittc dfto shafts byfan electric motor '16 having 'a'drivepulley 1 7, connected by a'belt llwith driven pulleys l9 onthe iower'end portions of the shafts. T he motor is 'conriectable with a source of 'energiiin'g current throughanormallyiclosed electric'switeh which can be I,

opened aut omaticallyto break the motor-energizing circuit in cylinders have'b'ee'n shown larger in diameter than the pump cylinders, they need not always be, as "their diameters are determined byv the pressure and delivery rate required-in the: I pump cylinders for the various products to be dispensed. j i

The actuator cylinders 23,24 are located above"t'heir respective-pump cylinders 'ahd are fixed to the pressure head in any suitable mantter The pump cylinders 25,26 have coaxial downward extensions which provide ductlike pumping chambers 27,28 eac'h directly below one ofthe' pumping cylinders. 25,2Q respectively, and in" open "communication therewith. The ductlike'pumping chambers 27 and 28 are Zfiixed to thle back of the piston member 8, in register with ports '29 and S lL'res'pectiveIy, in the piston member. Acheck valve- ?IU P' v d' df east! as P t wcl t ss s e ever pressure in: theassociated pumping chamber exceeds the pressure at the underside of the pistonmember 8.

. tion. The invention is not limited to the particular structure or method disclosed, and changes can be made therein which lie The ductlike pumping chambers 27 and- 28 are joined by a horizontal duct 32 that extends between them and cooperates therewith to provide a manifold to receive product displaced upwardly through the ports 29,30 upon descent of the piston member 8 into the product vessel 7, A delivery line 33 con communicates pumping chamber 28 with the delivery line.

When swung to the right, it communicates'the delivery line The single FIG. of the drawing more or less diagrammatically illustrates the dispensing apparatus of this invention, along with hydraulic and electrical control instrumentalities therefor. 1

As shown in the accompanying drawing, the dispensing apparatus of this invention comprises a substantiallycircular' base member 5, having a flat and horizontal upper surface 6, to receive and support the 5 gallon vessel 7 containing a viscous product to be dispensed, and a piston member 8 which is located directly over the basemember 5, and which is adapted to fit withinthe cylindrical sidewall 9 of a vessel in place on the base member to displace product therefrom upon relative movement between the piston andbase members to dispose them in closer relationship to one another.

nects with the duct 32, intermediate its ends, and is communicable with the pumping chambers 27,28 under the control of 3 a flap valve 34. The valve 34, when swung to the left as shown,

closes off the delivery line from pumping chamber 27 and with chamber 27 and closes it off from chamber 28. The flap valve, of course, is actuated to close off thedelivery line from either pumping chamber in response to predominating pressure in the other'chaniber. 1

Each of the actuator cylinders contains a piston 36 which is connected to the piston 37 in its associated pump cylinder by a common piston rod 38: The pistons 36 in the actuator cylinders collide with abutments 40 adjacent to the junctions of the f actuator and pump cylinders to limit downward travel of said pistons in their actuating strokes.

From the description thus far, it will be apparent. that product contained in the vessel 7 will be displaced-upwardly through one or member of the ports 29,30 therein, as a conedbythe pressurehead 1 sequence of downward propulsion of the piston member produced by rotation of the screw threaded drive shafts in one direction, or upon upward movement of the base member 5 relative to the piston member under the restoring force of the springs 12. It will also be appreciated that if either one of the pump pistons 37 is being driven downwardly by its actuator piston during displacement of product from the vessel under either of the conditions mentioned above, the downwardly driven pump piston will generate pressure in its associated pumping chamber of a magnitude such as to effect closure of its associated check valve 31 and to also hold the flap valve 34 in position communicating its associated pumping chamber with the delivery line.

Concurrently, with the above, product displaced from the vessel will flow upwardly past the other check valve and into the pumping chamber beneath the piston in the other pump cylinder to drive the same upwardly in its retraction or charging stroke, provided of course, that fluid is free to exhaust from the upper end of the actuator cylinder therefor.

From this, it will be seen that the pump cylinders are self charging, and that their actuator cylinders can be of the single acting type each having only one pressure fluid line connecting with its upper end, to communicate it with either a reservoir 42 or with the outlet of a pump 43 driven by an electric motor 44. As shown, one such line 45 is provided for cylinder 23, and the other cylinder 24 has its own pressure line 46.

It is also important to note that the force exerted by the pumping pistons is not transmitted to the vessel 7 through product therein, and pumping force is entirely independent from product-displacing force exerted on the product by piston member 8.

According to this invention, control means 47 is provided to assure that the upper ends of the actuator cylinders will be alternately vented to the reservoir and connected with the pump, in such synchronization that one such actuator cylinder will always be vented when pressure fluid is flowing into the other. Such control means comprises a reversing valve 48 by which either pressure line 45 and 46 can be connected with the pump while the other pressure line is connected to the reservior.

The reversing valve 48 has a valve element (not shown) which is movable to each of a pair of operating positions to effect such reversals in the pump and reservoir connections. If desired, the reversing valve may be actuated hydraulically in consequence of pressure changes in lines 45 and 46. Alternatively, a pair of solenoid actuators as indicated at 49 and 50 can be provided to effect shifting of its valve element from one to the other of its operating positions.

Energization of the solenoid 49 is controlled by a normally open pressure switch 51 that is adapted to close and complete an energizing circuit for the solenoid in response to the abrupt rise in pressure in line 45 that occurs at the conclusion of the actuating stroke of the piston in cylinder 23. Similarly solenoid 50 is energized by closure of a normally open pressure switch 52 in response to the abrupt rise in pressure in line 46 that occurs when the piston in cylinder 24 reaches the end of its actuating stroke.

The control system also comprises a third normally closed pressure switch 53, which is adapted to open whenever there is adequate dispensing pressure in the delivery line 33, to disrupt the energizing circuit for the pump motor 44. The pressure switch 53 responds to the pressure in the delivery line anywhere upstream from a valve 54 that controls discharge flow of the product through a dispensing nozzle 55.

As mentioned hereinbefore, the switch 20, when opened, breaks the energizing circuit to the electric motor 16 for the drive shafts 15. The contactor of the switch is adapted to be actuated to its switch open position by the extremity of a screw 57 adjustably threaded into a tab 58 projecting outwardly from the periphery of the base member 5, after the latter has been moved downwardly through and beyond a predetermined range of motion permitted by the springs 12 supporting the same. Opening of the switch 20, of course takes place before the force exerted on the product in the vessel increases to the point where the walls of the vessel might bulge or become ruptured. Such downward motion is indirectly imparted to the base member 5, to load springs 12, by the piston member 8 as the latter is forced downwardly against the product contained in the vessel 7. As soon as the switch 20 is opened, the descent of the piston member is halted, but displacement of product from vessel 7 continues uninterruptedly under the restoring force of springs 12, and until the motor 16 is again energized by the reclosure of switch 20 that takes place after a certain amount of upward motion of the base member.

It will be appreciated, of course, that switch 20 can be of the type wherein reclosure thereof can be delayed for a suitable interval, so that it does not immediately close as soon as the base member 5 begins to move upwardly relative to the piston member 8 under the restoring force ofthe springs 12.

To start operation of the apparatus with its components in their positions shown, and assuming that both pumping chambers are filled with product from the vessel 7, both the pump motor 44 and the motor 16 for the drive shafts 15 are energized as by closure of a line switch 60. This starts the shafts l5 rotating in the direction to effect descent of the piston member 8 toward the bed plate 10. Also, assuming that the control valve 48 had been actuated in consequence of closure of pressure switch 51 to its position communicating pump 43 with pressure line 46, while venting pressure line 45 to the reservoir, pressure fluid will flow into the upper end of actuator cylinder 24 to drive its piston 36 and that of pump cylinder 26 downwardly in its pumping stroke to keep its associated check valve 31 closed and to keep the flap valve in position to permit product to flow to the delivery line during the pumping stroke of the piston in cylinder 26.

The downward motion imparted to the piston member 8 by the screw threaded shafts 15 causes product from the vessel to be displaced upwardly through port 29 and into pumping chamber 27 to charge the pumping cylinder 25. This forces the piston 37 of pump cylinder upwardly, in its charging stroke, and the corresponding motion of the piston in its actuating cylinder exhausts the fluid in the upper end of the actuating cylinder to the reservoir through pressure line 45 and the control valve 48.

Consequently, the displaced product forces the piston in pump cylinder 25 upwardly in its charging stroke while pressure fluid delivered to actuator cylinder 24 causes the piston of pump cylinder 26 to be driven downwardly in its pumping stroke. As soon as piston 36 in the cylinder 24 bottoms on its abutment, the pressure rises abruptly in line 46 to effect closure of pressure switch 52. Solenoid 50 is energized by such closure of pressure switch 52 so as to cause reversal of the control valve 48 for connection of pressure line 45 with the pump 43 and communication of pressure line 46 with the reservoir 42. Then, the piston of pump cylinder 25 is driven downwardly in its pumping stroke to keep its associated check valve 31 closed and the flap valve in the opposite position allowing product pumped out of chamber 27 to flow to the delivery line, At the same time, product will be displaced upwardly through port 30 into pump cylinder 26 to charge the same. When downward motion of the piston 36 of actuator cylinder 23 is stopped by abutment 40, pressure switch 51 is actuated to closed position by the abrupt rise in pressure in line 45, to thus effect energization of solenoid 49. This again reverses valve 48 to start the cycle over again with cylinder 26 pumping and cylinder 25 charging.

If at any time during such pumpingof product into the delivery line the valve 54 is closed to stop flow of product out of the dispensing nozzle 55, the pressure in the delivery line quickly rises to the value at which pressure switch 53 is actuated to its open position, and the energizing circuit to the pump motor 44 is then disrupted to stop pumping of the product.

Thereafter, or at any other time, the piston member 8 may exert enough force on the product to move the base member 5 downwardly against the-action of its springs 12, through'and;

, beyond a predetermined range of'motion such as toeffect opening of switch 20.-The motor 'l6 from W'hichthe shafts 15 I threaded shaftsin the "opposite direction necessary for retraction of the piston member 8 from. the vessel a From the foregoing descriptionsto'gether with the accom-- panying drawings; it will be apparentto those-skilledintheart that this invention :provides an improved dispenseriforviscous productsrfeaturingpiston meansdriven by first-power means to effect displacement-of viscous product' froma vessel in which it isshipped'; along with second power means for pumping the displaced product'through 'a delivery tion of force on'the prodoctin the vessel. r

lclaimzt 1 f Y l. Dispensing apparatus comprising a piston member and a base member opposing the same. the base member being adapted to support a :yessel having jafsidewall providin'g'a cylinder to'slidably receive the piston member sothat moveline without exer- '4. The dispensing apparatus of claim wherein said means for driving the pump pistons co mprisesz" y Alan actuator cylinder for each pump cylinden'having fl. a diameter larger than. that of itsfassociated 'pump y nde 1 c f 2. a piston drivinglyiconnected with'the pistonof its as-- sociated pump. cylinder;

. 3; and a chamber into which" pressure" and can .be-

directedto effectthe' pumping stroke of its associated pumpipi stom'and from which pressure fluid can be exhaustedto provide'for} charging of its associated pump a cylinder with viscous product displaced'into its 85*,

i q i P p cy n er; v

B. a re i/ersiii 'valve'rnechanismforeftecting flow of pressure fluid to either chamber while concurrently providing forexhaust' flow of pressure fluid from the other chamber;

I C." and means for effecting reversal of said valve'fmechanism I v 'in consequence of the rise inpressure occurring in each ofsaid chambers at times vwhen theactuatOrpistonaS-' sociated therewith reaches the e'n d of its stroke.

I SIThe' dispensingapparatus of exam-14; further characterized by: y I

merit of one of said members toward the other effects dis placement of viscous product from the vessel through port 7 means in the piston member for flow to paratus beingcharacterized by: I I

A. said portmeans comprising a pair of portsopening t0. the

pressure faceof the piston membet5;;- r

B, a pair ofpu p; cylinders, one foreachiof said ports, to

a delivery line, said apreceive and beeharged bydis'placed prodiictdebouching from their respective ports', each of said pump cylinders having a piston which is driven in its retraction stroke by viscous product debouching into its cylinder;

C. a manifold lconnecting withlt'hepur'np cylinders to conduct viscous-product ekpelled' therefrom to the delivery line on the pumping strokes of their respective pistons;

D; pressure-:actuatable'valve means-operable'to close off i either pump cylinder from the delivery line in response to I the pressure produced in the other pump cylinder during I I the pumping stroke of its piston; I I E. a'checlt valee'associated'with eachtof said ports and'arranged toclose in responseto the pressu're obtaining in the associated pump cylinder on the pumping stroke of its Piston; 1 F. and means for driving the pump pistons.

B. yieldable means on the ,base structure supporting the I 2. The dispensing apparatus of claim 1 further cha cterized a base member for movementin one-direction relative to 3. The dispensing apparatisiof claim 2, further characterized by: v I A. said power operated means comprising an electric'motor; v B. and said control means comprising a normally closed electric switch controlling energization of the motor and connected with the base member to be opened thereby whenever the base member is moved beyond sai predetermined range. s I Y A. means providing asource of fluid underpressure, cornprising an electric motor driven pump;

.8. and a pressure switch for effectihgdeenerg'izat'ion of the" pump motor in response to attainment of a min'edihigh pressure in the delivery line. I I 6. Dispensing apparatus comprising apistonmemberahd a predete rba'se'member opposing'the same,' the"fbase memberbeing adapied S pp vessel having "a I sidewall providing fa cylinder to slidably receive the piston member so that movementof one of said members toward the other member efl'ects I I displacement of yiscous 'mducrnqm, the vessel throngh' 5 meansin the piston member forflow to a delivery line,said 'ap-- I paratt ls being characterized'by:

'A. first power operated means for driving one member toward the other to therebyj'effQGt displacement or "productIthrough saidport-means rene ban; of thepiston v nie'mben v B, chamber means'on the baekof the piston member com- -product'deboi ching therefrom: I I V I C. pump means spaced from the back of the piston member and communicating with said chamber means for pumpin'g product therefrom 'toarid along the deliveryline; 1 D. and means; for driving said 'piimp "means comprising power. operated means separate from said tirst "power operated means] 1 7; The dispensing apparatus of claim 6, further characterized by: l I

Asa pressure head from which the piston member is supported;

"'municating with said por'tfineans to receive'displaced B. and said pump means being carried. by the pressure head.

' means. I

9..The dispensing apparatus of claim 6, wherein the piston member comprises said one member, and wherein said first power operated means comprises:

A. a power source; I B. a pressure head to which the piston member is fixed;

C. and means drivingly connecting the power source with said pressure head to move the same and the piston member therewith as a unit toward the base member.

10. The dispensing apparatus of claim 6, wherein said displacement of product from the, vessel is effected in consequence of movement of the piston member toward the base member, and further characterized by:

A. a pressure head to which the piston member is flared; B. a bed plate from which the base member is supported; Cfa plurality of screw threaded shafts freely rotatably jour naled in the bed plate and having screw threaded connec tions with the pressure head; I I 1 D, an electric motor carried by the bed plate;

E. and means drivingly connecting the motor with said shafts.

ll. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other member effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by:

A. an electric motor operatively connected with the piston member to drive the same in one direction toward the base member;

B. chamber means communicating with said port means to receive displaced product debouching therefrom;

C. pump means for pumping product from said chamber means to and along the delivery line;

D. a bed plate to support the base member;

E. spring means connected between the bed plate and the base member to yieldingly support the same against the thrust of the piston member transmitted thereto through the product being dispensed from a vessel on the base member, whereby the base member can move relative to the bed plate in said direction;

F. and switch means actuated in response to motion of the base member in said direction through and beyond a predetermined range of motion for effecting disruption of the energizing circuit for the motor.

12. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other member effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by:

A. power operated means for 'gdriving said one member toward the other to thereby effect displacement of product through said port means in the piston member, said power operated means comprising a motor drivingly connected with the piston member;

B. chamber means communicating with said port means to receive displaced product debouching therefrom;

C. pump means for pumping product from said chamber means to and along the delivery line;

D. spring means mounting the base member for yielding motion under the thrust of the piston member;

E. and means for rendering the motor ineffective in response to a predetermined amount of yielding motion of the base member. 

1. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by: A. said port means comprising a pair of ports opening to the pressure face of the piston members; B. a pair of pump cylinders, one for each of said ports, to receive and Be charged by displaced product debouching from their respective ports, each of said pump cylinders having a piston which is driven in its retraction stroke by viscous product debouching into its cylinder; C. a manifold connecting with the pump cylinders to conduct viscous product expelled therefrom to the delivery line on the pumping strokes of their respective pistons; D. pressure actuatable valve means operable to close off either pump cylinder from the delivery line in response to the pressure produced in the other pump cylinder during the pumping stroke of its piston; E. a check valve associated with each of said ports and arranged to close in response to the pressure obtaining in the associated pump cylinder on the pumping stroke of its piston; F. and means for driving the pump pistons.
 2. The dispensing apparatus of claim 1 further characterized by: A. a base structure from which the base member is supported; B. yieldable means on the base structure supporting the base member for movement in one direction relative to the base structure in consequence of force required to expel viscous product from a vessel on the base member; C. power operated means for effecting motion of said one member toward the other member; D. and control means for said power operated means, for rendering the same inoperative in response to movement of the base member in said direction relative to the base structure beyond a predetermined range of such relative movement.
 2. a piston drivingly connected with the piston of its associated pump cylinder;
 3. and a chamber into which pressure fluid can be directed to effect the pumping stroke of its associated pump piston, and from which pressure fluid can be exhausted to provide for charging of its associated pump cylinder with viscous product displaced into its associated pump cylinder; B. a reversing valve mechanism for effecting flow of pressure fluid to either chamber while concurrently providing for exhaust flow of pressure fluid from the other chamber; C. and means for effecting reversal of said valve mechanism in consequence of the rise in pressure occurring in each of said chambers at times when the actuator piston associated therewith reaches the end of its stroke.
 3. The dispensing apparatus of claim 2, further characterized by: A. said power operated means comprising an electric motor; B. and said control means comprising a normally closed electric switch controlling energization of the motor and connected with the base member to be opened thereby whenever the base member is moved beyond said predetermined range.
 4. The dispensing apparatus of claim 1, wherein said means for driving the pump pistons comprises: A. an actuator cylinder for each pump cylinder; having
 5. The dispensing apparatus of claim 4, further characterized by: A. means providing a source of fluid under pressure, comprising an electric motor driven pump; B. and a pressure switch for effecting deenergization of the pump motor in response to attainment of a predetermined high pressure in the delivery line.
 6. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other member effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by: A. first power operated means for driving said one member toward the other to thereby effect displacement of product through said port means to the back of the piston member; B. chamber means on the back of the piston member communicating with said port means to receive displaced product debouching therEfrom; C. pump means spaced from the back of the piston member and communicating with said chamber means for pumping product therefrom to and along the delivery line; D. and means for driving said pump means comprising power operated means separate from said first power operated means.
 7. The dispensing apparatus of claim 6, further characterized by: A. a pressure head from which the piston member is supported; B. and said pump means being carried by the pressure head.
 8. The dispensing apparatus of claim 7, wherein the piston member is rigidly joined to the pressure head by said pump means.
 9. The dispensing apparatus of claim 6, wherein the piston member comprises said one member, and wherein said first power operated means comprises: A. a power source; B. a pressure head to which the piston member is fixed; C. and means drivingly connecting the power source with said pressure head to move the same and the piston member therewith as a unit toward the base member.
 10. The dispensing apparatus of claim 6, wherein said displacement of product from the vessel is effected in consequence of movement of the piston member toward the base member, and further characterized by: A. a pressure head to which the piston member is fixed; B. a bed plate from which the base member is supported; C. a plurality of screw threaded shafts freely rotatably journaled in the bed plate and having screw threaded connections with the pressure head; D. an electric motor carried by the bed plate; E. and means drivingly connecting the motor with said shafts.
 11. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other member effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by: A. an electric motor operatively connected with the piston member to drive the same in one direction toward the base member; B. chamber means communicating with said port means to receive displaced product debouching therefrom; C. pump means for pumping product from said chamber means to and along the delivery line; D. a bed plate to support the base member; E. spring means connected between the bed plate and the base member to yieldingly support the same against the thrust of the piston member transmitted thereto through the product being dispensed from a vessel on the base member, whereby the base member can move relative to the bed plate in said direction; F. and switch means actuated in response to motion of the base member in said direction through and beyond a predetermined range of motion for effecting disruption of the energizing circuit for the motor.
 12. Dispensing apparatus comprising a piston member and a base member opposing the same, the base member being adapted to support a vessel having a sidewall providing a cylinder to slidably receive the piston member so that movement of one of said members toward the other member effects displacement of viscous product from the vessel through port means in the piston member for flow to a delivery line, said apparatus being characterized by: A. power operated means for driving said one member toward the other to thereby effect displacement of product through said port means in the piston member, said power operated means comprising a motor drivingly connected with the piston member; B. chamber means communicating with said port means to receive displaced product debouching therefrom; C. pump means for pumping product from said chamber means to and along the delivery line; D. spring means mounting the base member for yielding motion under the thrust of the piston member; E. and means for rendering the motor ineffective in response to a predetermined amount of yielding motion of the base member. 